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Why Are Our Brains So Big? Scientists Have a Few Possible Answers

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Human brains are big. They account for about 2 percent of our body mass—a higher percentage than most other species—and they’re triple the size of those belonging to our common ancestor, the ape-like Australopithecines. While there’s no consensus on how and why our brains got to be so big, scientists have suggested a new theory that contradicts earlier ideas.

As phys.org reports, a study published in the journal Nature contains evidence that the human brain evolved in response to ecological stress. Faced with a harsh environment, the brain grew to help humans better survive and provide for their offspring, the scientists believe. Previously, studies suggested that the brain evolved as humans began to engage in more complex social interactions. The researchers behind this new study say their findings suggest otherwise.

“The findings are intriguing because they suggest that some aspects of social complexity are more likely to be consequences rather than causes of our large brain size,” Mauricio González-Forero, the paper’s co-author and a mathematical evolutionary biologist at Scotland’s University of St. Andrews, tells phys.org. “The large human brain is more likely to stem from ecological problem-solving and cumulative culture than it is from social maneuvering.”

They reached this conclusion by using computer software to simulate evolution. Data relating to how much energy an adult human female needs to support the brain was plugged in, as well as energy requirements relative to body size, the Indiana Gazette reports.

Overall, researchers determined through their model that the main challenges that spurred brain growth were overwhelmingly (60 percent) ecological in nature, but it also may have resulted from cooperation (30 percent) and competition between groups (10 percent). Researchers said the ability to acquire new skills is also a crucial component when considering how human brains evolved.

“Ecological challenges can only lead to brain size of this scale if they are coupled with the ability to continue learning from others,” González-Forero said. “The paper is suggesting that human brain development is an interaction between these two things—ecological pressures and culture.”

[h/t phys.org]

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Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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Uncombable Hair Syndrome Is a Real—and Very Rare—Genetic Condition
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Everyone has bad hair days from time to time, but for roughly 100 people around the world, unmanageable hair is an actual medical condition.

Uncombable hair syndrome, also known as spun glass hair syndrome, is a rare condition caused by a genetic mutation that affects the formation and shape of hair shafts, BuzzFeed reports. People with the condition tend to have dry, unruly hair that can't be combed flat. It grows slower than normal and is typically silver, blond, or straw-colored. For some people, the symptoms disappear with age.

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Although there have been only about 100 documented cases worldwide, one of the world's leading researchers on the condition, Regina Betz, of Germany's University of Bonn, believes there could be thousands of others who have it but have not been diagnosed. Some have speculated that Einstein had the condition, but without a genetic test, it's impossible to know for sure.

An 18-month-old American girl named Taylor McGowan is one of the few people with this syndrome. Her parents sent blood samples to Betz to see if they were carriers of the gene mutation, and the results came back positive for variations of PADI3, one of three genes responsible for the syndrome. According to IFL Science, the condition is recessive, meaning that it "only presents when individuals receive mutant gene copies from both parents." Hence it's so uncommon.

Taylor's parents have embraced their daughter's unique 'do, creating a Facebook page called Baby Einstein 2.0 to share Taylor's story and educate others about the condition.

"It's what makes her look ever so special, just like Albert Einstein," Taylor's mom, Cara, says in a video uploaded to YouTube by SWNS TV. "We wanted to share her story with the world in hopes of spreading awareness."

[h/t BuzzFeed]

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